Pipette



(No Model.)

' Y P. M. SHARPLES.

* PIPBTTE. ,N0553,044. 'PatentedJanl 14, 1896.

VVitnesses:

UNITED STATES PATENT EEIcEe PHILIP M. SHARPLES, OF "WEST CHESTER,PENNSYLVANIA.

PlPETTE.

SPECIFICATION forming part of Letters Patent No. 553,044, dated January14, 1896. l Application filed December 4,. 1894. Renewed December 13,1895. Serial No. 572,045. (No model.)

To @ZZ whom it 11i-ay concern:

Be it known that I, PHILIP M. SIIAEPLES, a citizen of the United States,residing at West Chester, county of Chester, State of Pennsylvania, haveinvented certain Improvements in Pipettes, ot' which the following is aspecilication.

My invention relates to measuring devices which are especially adaptedfor rapidly and accurately measuring uniform quantities of liquids.

In a pending application of David T. Sharples, Serial No. 457,086, filedOctober 3, lSJS, is shown and described an automatic pipette comprisinga measuring-tube having one of its open ends arranged in communicationWith an air-tight overflow-chamber having a pump connection by means ofwhich suction is exerted through said overflow-chamber to iill themeasuring-tube to overflowing and thereafter hold the measured liquiduntil the saine is discharged by the reversal of the pump action.- Themain object of my invention is to provide a device of this kind havingmeans separate from the pump connection, whereby to hold or release themeasured liquids.

The invention is described in connection with the accompanying drawingsand is specitically pointed out in the claims.

Figure l illustrates a pipette embodying my invention in its simplestform. Fig. 2 shows a modified arrangement, and Fig. 3 a different formof stopper-valve applicable to the construction shown in Fig. l.

A represents a measuring tube having openings a and a", and of anydesired capacity.

B is an overi'loivchamber inclosing the open end a of themeasuring-tube. This overflow-vessel is provided With a pumpconnection?) and with an open neck b'. In Eig. l this neck b' is tightlyclosed by a stopper C in the `form of a flexible disk of rubber or othersuitable material, and the open end a of the measuring-tube is extendedinto such proximity to the disk as to permit the latter to be depressedinto contact with it so as to seal the opening a.. The pump connection bmay be provided With a iieXible bulb D, in which case the device isoperated by rst compressing this, then inserting the opening d' of themeasuring-tube in the liquid, releasing the bulb to fill the tube, andas soon as the latter overiiows at a depressing the stoppervalve C toclose the tube, and thus securely hold the liquid until it is conveyedto the delivery-point, when the valve C is raised and the liquidreleased; or the pump connection may be extended, as indicated in dottedlines, and the mouth of the operator applied thereto as al means ofexhausting the air from the overflow-chamber, the suction being stoppedas soon as the overflow appears and the stopper-valve simultaneouslyclosed. The disk C is preferably made of moderately-heavy rubber,sufficiently stii to prevent its being drawn to its seat upon themeasuring-tube by the suction exerted through the pump connection, thepressure of the operators linger being preferably utilized to effectthis closing of the tube andthe elasticity of the disk serving to openit when released.

In the modified construction shown in Eig. l the pump connection b isprovided With a check-valve b2 and the open neckV b' of theoverflow-vessel is closed by the operator While the liquid is beingdrawn into the tube by suction at l). Then the liquid overflows the tubeat a the suction is stopped, and the check-valve drops to its seat, andthe measured liquid is held until released by uncovering the opening b'.

In the modied form of stopper-valve shown in Fig. 3 a hollow stopper C'is employed in connection with a flexible valve c, and a button c forseating the same upon the end of the measuring-tube.

Having thus fully described my invention in connection with several ofmany modications which may be devised, I do not desire to limit myselfto the specific construction shown, but

That I claim isl. A measuring device for liquids comprising a measuringtube open at two points, an overilow chamber arranged in communicationwith one of said openings, a pump connection to said overiiow chamber,and means separate from said pump connection adapted to operate uponsaid overflow opening of the measuring tube to hold or discharge theliquid therein, substantially as set forth.

2. A measuring device for liquids comprising a measuring tube open attwo points, an overiiovv chamber arranged in communica- IOO neetion7and-a stopper valve fitted to said neck and adapted to open 0r Closesaid communicating Opening of the measuring tube.

substantially as set forth. r 5

In testimony whereof I aiix my signature in presence of two Witnesses.

PHILIP M. SHARPLES. lVtnesses ADDAv E. WORRALL, XVM. S. WINDLE.

